BE1028518B1 - Silicone formulation comprising an oxime crosslinker, cured silicone formulation and applications thereof - Google Patents

Abstract

The present invention relates to a silicone formulation comprising an oxime-silane cross-linker comprising 5-methyl-3-heptanone oxime, which exhibits significantly improved early cracking behavior and/or improved sheeting time compared to silicone formulations using conventional oxime-silane cross-linkers. the corresponding cured silicone formulation, uses of the cured silicone formulation, and uses of such oxime crosslinkers in the silicone formulation field. The present invention also relates to an oxime crosslinker.

Description

BE2021/5640 Silicone formulation comprising an oxime crosslinker, cured silicone formulation and uses thereof Field of the Invention

The present invention relates to a silicone formulation comprising an oxime crosslinker, the corresponding cured silicone formulation, uses of the cured silicone formulation and uses of oxime crosslinkers in the field of silicone formulations. The present invention also relates to an oxime crosslinker.

State of the art

Room temperature vulcanizable compositions comprising a polydiorganosiloxane, also called RTV silicones, are known and used in various applications. Its most common use is in the building and construction field, where RTV silicone is used as a sealant, adhesive or coating. Such silicones typically comprise a polydiorganosiloxane with reactive hydroxyl end groups as the base polymer in combination with a crosslinking agent and optional components such as catalysts, fillers, pigments, dyes, lubricants, plasticizers, adhesion promoters, thickeners, etc. Depending on the reactivity of the components and the desired shelf life, an RTV silicone can be formulated as a single component, where all components are mixed, or as a multi-component formulation, where different components comprise different (portions) of components and must be combined prior to use. The most commonly used silicone formulations are single component (RTV1) or two component (RTV2) formulations, which are typically moisture curable and employ a triple or quadruple functional silane (or its corresponding siloxane condensation product) as a crosslinker.

The ready-to-use, moisture-curable silicones are traditionally sold pre-condensed with the polydiorganosiloxane and the silane crosslinker and used in the form of a so-called "prepolymer" or "end-capped" polysiloxane. During production of these moisture curable silicones, the terminal hydroxyl groups of the polydiorganosiloxane react with the triple or quadruple functional silane (or its corresponding siloxane condensation product) as a crosslinker to form the so-called 'prepolymer' which can then cure. by cross-linking under the influence of atmospheric moisture. This first reaction step is also called 'end-capping', i.e. the addition of another end group on the reactive polydiorganosiloxane, and the resulting product can thus also be called an 'end-capped polymer'. Because this step leads to the formation of a "prepolymer", i.e. a compound suitable for further polymerization, this step is often also referred to as "prepolymerization". This step prepares the reactive polymer for the next polymerization reaction without being a polymerization reaction itself.

Subsequently, after releasing the end-capped polysiloxane from its container (e.g. when applying the silicone to the desired substrate), moisture curing takes place

© BE2021/5640 place. The end-capped polymer has two (if the silane crosslinker was triple functional) or three (if the silane crosslinker was quadruple functional) residual reactive groups. Without wishing to be bound by theory, it is believed that environmental moisture upon application of the silicone paste hydrolyzes these residual reactive groups to even more reactive silanol groups which in turn cross-link other end-capped polymer chains. Since the cross-linking agent has applied two or three reactive groups to each end of the original polydiorganosiloxane, a three-dimensional, cross-linked end structure can be formed in this way.

The commonly used silane crosslinkers are acidic (e.g., ethyl-tris(acetoxy)silane) or neutral cross-linkers (e.g., methyl-tris(methylethylketoxime)silane) based on the leaving groups released during hydrolysis. Acid cross-linkers have traditionally been the most important group. However, in view of possible substrate degradation caused by the acid released during cross-linking, the sub-optimal substrate adhesion and the often pungent and unpleasant odor, systems based on neutral cross-linkers such as oxime silanes are currently being developed.

The most common and most economically successful oxime-silane crosslinker uses methylethylketoxime (MEKO). However, RTV silicones using MEKO or similar oxime-based silane cross-linkers have a number of shortcomings. For example, many known oxime crosslinkers are solid or highly viscous at room temperature or tend to form solid particles resulting from crystallization of the leaving group of the oxime, which complicates the manufacture of the silicone formulation. Interestingly, some hydrolysis products of oxime cross-linkers, such as 2-butanone oxime (generated from hydrolysis of MEKO end-capped siloxane during curing) have been associated with a carcinogenic effect.

In order to be practical, particularly when used as a sealant or jointer, RTV silicone formulations must not only have desirable physical properties after curing, but must also be 'workable', for example by allowing for an appropriate sheeting time. and exhibit little or preferably no early cracking behaviour.

The skinning time of a silicone formulation is the time from application to the onset of superficial solidification (skin formation" and characterizes the time in which it is possible to manipulate the sealant after application (e.g. extrusion from a container). is important, as in practice a sealant is first applied to a seam and then 'smoothed' using a soap-dipped finger or a specific tool.

Early cracking behavior is the (in)ability of a sealant to resist deformations at the early stage of sealant curing. Typical sealants with poor early cracking behavior tend to crack in the seam when seam deformation occurs shortly after application of the sealant 40. In practice, this can occur in the event of a

° BE2021/5640 temperature change in seams combining materials with high or different coefficients of thermal expansion, or as a result of (human) manipulation of the seam shortly after application of the sealant, e.g. someone simply getting in and out of a bathtub being sealed already cause movement of the seam by a few millimeters.

As will be shown in the accompanying examples, the present inventors have found that silicone formulations using known oxime-based silane crosslinkers exhibit short sheeting time and/or a large window for early cracking.

Therefore, there is a need for crosslinking agents that can be used in an RTV silicone formulation, especially a sealant formulation, which overcome one or more problems of the prior art.

It is an object of the present invention to provide a silane cross-linker and/or a silicone formulation comprising the cross-linker, which is characterized by a prolonged sheeting time and/or shortened early cracking time, e.g. compared to a known silane-forming agent. cross-linker based on oxime.

It is a further object of the present invention to provide a silane crosslinker and/or a silicone formulation comprising the crosslinker which has a reduced release of carcinogenic compounds and preferably leads to a reduced intensity and/or time of malodor after curing, preferably compared to a known oxime-based silane cross-linker. Summary of the invention

As shown in the accompanying examples, the present inventors have surprisingly found that silicone formulations utilizing an oxime-silane crosslinker comprising 5-methyl-3-heptanone oxime exhibit significantly improved early cracking behavior and/or improved sheeting time compared to silicone formulations. using conventional oxime-silane cross-linkers. In addition, the 5-methyl-3-heptanone oxime released from the silicone formulation during moisture curing has low volatility and may have reduced or no carcinogenic effects and/or malodor compared to known oxime-silane cross-linkers such as MEKO silanes .

The present inventors have further found that the improved early cracking behavior and/or the improved sheeting time can be obtained by using the oximes as their triple or quadruple functional silanes tris(5-methyl-3-heptanone oxime) silane or tetra(5-methyl-3-heptanone oxime) silane, as well as when 5-methyl-3-heptanone oxime is used as free oxime in combination with a silane or siloxane crosslinker. Without wishing to be bound by theory, the present inventors believe that the combination of 5-methyl-3-heptanone oxime as free oxime with a silane or siloxane cross-linker leads to the in-situ formation of a 5-methyl-3 - heptanone oximesilane.

Accordingly, in a first aspect, the invention provides a silicone formulation comprising a hydroxy-terminal polydiorganosiloxane and a first crosslinker selected from silanes of formula (I) and hydrolysis or condensation products thereof: ? ve í 5 Js Ri Ob Si —/0 RA | NX X x % % Ï ; À X À / 4 Bf X se (1) where: a is 0,1,2or3; boof1 is; c is 1, 2, 3 or 4; a+b+c4is; each occurrence of R1 and R2 is individually selected from the group consisting of hydrogen and optionally substituted monovalent hydrocarbon radicals having 1 to 30 carbon atoms and R3 and R* are such that each occurrence of R3 is methyl and R* is hydrogen.

As will be appreciated by those skilled in the art from the present disclosure, the compound of formula (I) is an oxime-silane cross-linker comprising at least one 5-methyl-3-heptanone oxime group.

In another aspect, the present invention provides an oxime silane or siloxane crosslinker selected from silanes of formula (I) and hydrolysis or condensation products thereof: (we, X 3 '2 Re Oei DR 4 'A & 4 5 % © $ N= X { OA X Ï ; | OR | \ ; Ï X / ; x * !

X R5 X R1 (1) wherein: a, b, c, R*, R2, R3 and R* are as defined above.

In another aspect there is provided a cured silicone elastomer obtainable by curing the silicone formulation as described herein, preferably obtainable by moisture curing the silicone formulation as described herein.

° BE2021/5640

In another aspect, use of the silicone formulation or cured silicone elastomer provided herein is provided as a sealant, joint compound or adhesive, preferably as a sealant.

In another aspect of the invention, various uses of a first crosslinker selected from silanes of formula (I) and hydrolysis or condensation products thereof as described herein are provided.

In another aspect of the invention there are provided methods for preparing the silicone formulations as described herein comprising the steps of: (providing at least one hydroxy-terminal polydiorganosiloxane as described herein; (il) providing: (1.1) a first crosslinker selected from silanes of formula (1) and hydrolysis or condensation products thereof as defined herein: (1.2) optionally a second silane or siloxane crosslinker selected from silanes of formula (II) as described herein and hydrolysis - or condensation products thereof, (ill) optionally providing further ingredients, and (iv) combining the ingredients provided in steps (i), (ii) and optionally (iii).

Reference is made to substances, components or components existing just prior to first contacting, combining or mixing with one or more other substances, components or constituents in accordance with the present disclosure. A substance, component or constituent may acquire an identity, property or character through a chemical reaction or transformation during the course of contacting, combining or mixing when performed in accordance with this description with the application of common sense and the usual skills of a average chemist. Unless otherwise specified herein, definitions of substances, components or ingredients and their relative amounts refer to the composition as prepared at the time of first contact of the ingredients, unless expressly stated otherwise. For example, it is known to those skilled in the art that contacting a hydroxy-terminal polydiorganosiloxane as described herein with a silane crosslinker as described herein can lead to end-capping of the polydiorganosiloxane. As explained elsewhere herein, end capping is typically performed on purpose by combining the polydiorganosiloxane with the crosslinker and optionally a catalyst before addition of the remaining components. Whenever reference is made herein to a composition or the preparation of a composition comprising a hydroxy-terminal polydiorganosiloxane, a crosslinker and optional further ingredients, unless otherwise indicated, this expressly includes compositions wherein the hydroxy-terminal polydiorganosiloxane is end-capped. with a cross-linker or with the cross-linker described in the composition.

° BE2021/5640

In a first aspect, the invention provides a silicone formulation comprising a hydroxy-terminal polydiorganosiloxane and a first crosslinker selected from silanes of formula (I) and hydrolysis or condensation products thereof: Ri Ob Si —o RN {NS \ | > À PL | \ © À (D where: a0,1,20f3is; bOof1; c is 1, 2, 3 or 4; a+b+c4is; each occurrence of R' and R2 is individually selected from the group consisting of hydrogen and optionally substituted monovalent hydrocarbon radicals having 1 to 30 carbon atoms and R3 and R* are such that each occurrence of R3 is methyl and R* is hydrogen.

In one embodiment, the silicone formulation as defined herein further comprises a catalyst, preferably an organometallic catalyst present in an amount of 0.01-10% by weight (based on total weight of the silicone formulation). Crosslinker according to formula (!)

As previously explained herein and as shown in the examples, the present inventors have found that silicone formulations using a crosslinker selected from silanes of formula (I) have several special and favorable properties, such as reduced or even no early cracking behaviour, prolonged skin formation time, reduced release of hazardous (eg carcinogenic) compounds or odor during curing.

As is known to the skilled person, silane crosslinkers can be used as such or they can be (partially) hydrolyzed and/or condensed to form corresponding short chain polysiloxanes. Such hydrolysis and/or condensation often already occurs to some extent as a result of interaction of the silane crosslinker with trace amounts of water before, during or after preparing the silicone formulation. Thus, those skilled in the art will appreciate that the silane crosslinkers described herein may be provided as such or in the form of a hydrolysis or condensation product thereof. In particularly preferred embodiments, the first crosslinker is selected from silanes of formula (D and hydrolysis or condensation products thereof) selected from silanes of formula (1).

/ BE2021/5640

In preferred embodiments of the invention there is provided the silicone formulation comprising a first crosslinker selected from silanes of formula (D) and hydrolysis or condensation products thereof, as described herein, wherein: each occurrence of R! individually selected from the group consisting of hydrogen, C1 -C8 alkyl, C1 -C8 haloalkyl, C1 -C8 aminoalkyl, C2 -C8 alkenyl, C3 -C8 cycloalkyl, C4 -C8 cycloalkenyl, C6 -C10 aryl, -C(O)R5 , -NECRER7 and -N=CRS:; RS, Rc and R' are selected from the group consisting of C1-C8-alkyl, C2-C8-alkenyl, C3-C8-cycloalkyl, C4-C8-cycloalkenyl and C3-C10-aryl; R 3 is a divalent C 2 -C 8 alkyl radical, so that -N=CR 3 is a cycloalkyl and R? is selected from the group consisting of hydrogen, C1 -C4 alkyl, C2 -C4 alkenyl and phenyl.

In a particularly preferred embodiment of the invention there is provided the silicone formulation comprising a first crosslinker selected from silanes of formula (I) and hydrolysis or condensation products thereof, as described herein, wherein: a is 0; b is O or 1, preferably 1; c is 3 or 4, preferably 3; a+b+c4is; R? is selected from the group consisting of hydrogen, C1 -C4 alkyl, C2 -C4 alkenyl and phenyl, preferably R1 . is selected from the group consisting of hydrogen, methyl, ethyl, vinyl and phenyl, more preferably R2 is methyl and R3 and R* are such that each occurrence of R* is methyl and R* is hydrogen. As will be understood by those skilled in the art from the present disclosure, this embodiment corresponds to the use of the oximes of the invention as a tris(5-methyl-3-heptanoneoxime)silane or as the quadruple functional tetra(5-methyl -3-heptanone oxime) silane. Furthermore, the inventors have found that using these oximes in the form of their triple-functional methylsilanes (i.e., R2 is methyl) has the additional advantage of increasing the sheeting time as compared to the corresponding vinyl silanes (i.e., R2 is vinyl) and that the skin formation time is prolonged. cured silicones are not tacky. The latter is particularly an issue with the corresponding phenylsilanes (i.e. R2 is phenyl), which remain tacky for a long time after curing.

In a particularly preferred embodiment of the invention there is provided the silicone formulation comprising a first crosslinker selected from silanes of formula (I) and hydrolysis or condensation products thereof, as described herein, wherein the first crosslinker selected from silanes of formula (I ) and hydrolysis or condensation products thereof is a tris(5-methyl-3-heptanone oxime) silane, preferably a tris(5-methyl-3-heptanone oxime) silane selected from the group consisting of methyl-tris(5-methyl-3 - heptanone oxime) silane, vinyl-tris(5-methyl-3-heptanone oxime) silane and phenyl-tris(5-methyl-3-heptanone oxime) silane, most preferably methyl-tris(5-methyl-3-heptanone oxime) silane .

[0031] In a particularly preferred embodiment of the invention, the silicone formulation is provided comprising a first crosslinker selected from silanes of formula (I) and

° BE2021/5640 hydrolysis or condensation products thereof, as described herein, wherein the first crosslinker selected from silanes of formula (I) and hydrolysis or condensation products thereof is tetra(5-methyl-3-heptanone oxime) silane.

In a particularly preferred embodiment of the invention there is provided the silicone formulation comprising a first crosslinker selected from silanes of formula (I) and hydrolysis or condensation products thereof, as described herein, wherein: a is 2 or 3; boof1 is; c is 1 or 2; a+b+c4is; each occurrence of R' is individually selected from the group consisting of C1 -C4 alkyl, C2 -C4 alkenyl, phenyl, -C{O)R5, -N=CRSR7 and -N=CR8; RS, Rc and R' are selected from the group consisting of C1-C8-alkyl, C3-C8-cycloalkyl and phenyl; R3 is a divalent C5 alkyl radical such that -N=CR3 is cyclohexyl; R? is selected from the group consisting of hydrogen, C1 -C4 alkyl, C2 -C4 alkenyl and phenyl and R3 and R* are such that each occurrence of R3 is methyl and R* is hydrogen. As will be understood by those skilled in the art from the present disclosure, this embodiment is equivalent to using 5-methyl-3-heptanone as free oxime in combination with a silane or siloxane crosslinker. Without wishing to be bound by theory, the present inventors believe that the combination of 5-methyl-3-heptanone as free oxime with a silane or siloxane cross-linker leads to the in-situ formation of a 5-methyl-3 - heptanone oximesilane or siloxane.

The present inventors have found that the combination of 5-methyl-3-heptanone as free oxime with an oximesilane or siloxane cross-linker is particularly beneficial. As shown in the examples, the combination with 2-pentanone oximesilanes (also called methylpropyl-ketoximosilanes) has been found to be the most preferred, resulting in a silicone formulation that exhibits increased sheet time, improved early cracking properties and improved mechanical properties (modulus of elasticity, elongation at break). and/or shore A hardness). Thus, in preferred embodiments of the invention, there is provided the silicone formulation comprising a first crosslinker selected from silanes of formula (1) and hydrolysis or condensation products thereof, as described herein, wherein a is 2 or 3; boof1 is; c is 1 or 2; a+b+c4is; R? is selected from the group consisting of hydrogen, C1 -C4 alkyl, C2 -C4 alkenyl and phenyl and R3 and R* are such that each occurrence of R3 is methyl and R* is hydrogen; R! -N=CRSR' and RS and R7 are selected from the group consisting of C1-C8 alkyl, preferably wherein R° is methyl and 40 RR' is propyl.

) BE2021/5640

In a preferred embodiment of the invention there is provided the silicone formulation comprising a first crosslinker selected from silanes of formula (D) and hydrolysis or condensation products thereof as described herein, wherein the total amount of silanes of formula (1) and hydrolysis - and condensation products thereof is in the range of 0.1 to 15% by weight (based on total weight of the silicone formulation), preferably in the range of 0.5 to 10% by weight, more preferably in the range of 1 up to 6% by weight.

In particularly preferred embodiments of the invention, the silicone formulation is provided as described herein, wherein the hydroxy-terminal polydiorganosiloxane is at least partially end-capped with the first cross-linker.

Second cross-linker

The silicone formulations of the invention may comprise one or more additional cross-linking agents. In some embodiments of the invention there is provided the silicone formulation comprising a first crosslinker selected from silanes of formula ([) and hydrolysis and condensation products thereof as described herein, and further comprising a second silane or siloxane crosslinker.

In preferred embodiments of the invention there is provided the silicone formulation comprising a first crosslinker selected from silanes of formula (D) and hydrolysis and condensation products thereof as described herein, and further comprising a second silane or siloxane crosslinker selected from silanes of formula (I) and hydrolysis and condensation products thereof: (IN) wherein d is 3 or 4, preferably 3; e is 1 or O0, preferably 1; d+e4is; each occurrence of R° is individually selected from the group consisting of hydrogen and optionally substituted monovalent hydrocarbon radicals having 1 to 30 carbon atoms, preferably each occurrence of R° is individually selected from the group consisting of hydrogen, C1-C8 alkyl, C1-C8-haloalkyl, C1-C3-aminoalkyl, C2-C8-alkenyl, C3-C8-cycloalkyl, Ca-C8-cycloalkenyl, C5-C10-aryl, -C(O)R'11, -N=CR' 2R13 and -N=CR"*, more preferably each occurrence of Rc is individually selected from the group consisting of C1 -C4 alkyl, C2 -C4 alkenyl, phenyl, -C(O)R11, -N= CR'2R13 and -N=CR"*, most preferably R° is NECR"?R*; R11, R2 and R°° are selected from the group consisting of C1-C8 alkyl, C2-C8 alkenyl, C 3 -C 8 cycloalkyl, C 4 -C 8 cycloalkenyl and C 6 -C 10 aryl, preferably R 11 , R 12 and R 13 are selected from the group consisting of C 1 -C 4 alkyl, most preferably R 11 and R 12 are methyl and R °3 is propyl; R1* is a divalent C2 -C8 alkyl radical such that -N=CR"* is a cycloalkyl and

R1 is selected from the group consisting of hydrogen and optionally substituted monovalent hydrocarbon radicals having 1 to 30 carbon atoms, preferably R10 is selected from the group consisting of hydrogen, methyl, ethyl, vinyl and phenyl, more preferably R10 is methyl.

As will be appreciated by those skilled in the art, the second silane or siloxane crosslinker selected from silanes of formula (II) and hydrolysis or condensation products thereof differs from the first crosslinker selected from silanes of formula (I) and hydrolysis or condensation products thereof.

As will be shown in the accompanying examples, the present inventors have found that the combination of a first crosslinker selected from silanes of formula (I) and hydrolysis or condensation products thereof, as described herein, with a second silane or siloxane crosslinker selected from tris-(methylpropylketoximo)methylsilane, tris(methylpropylketoximo)vinylsilane and tris(methylpropylketoximo)phenylsilane, especially tris(methylpropylketoximo)methylsilane, is particularly beneficial and providing a formulation with sufficiently long sheeting time, little or does not allow early cracking and good mechanical properties. Similar formulations using conventional cross-linkers such as methyl tris(acetone oximo) silane or methyl tris (methyl ethyl ketoximo) silane as a second silane or siloxane cross-linker have been found to have inferior properties, particularly in sheet formation time and/or the mechanical properties, and/or larger amounts of the first crosslinker to exhibit satisfactory properties.

In embodiments of the invention there is provided the silicone formulation comprising a first crosslinker selected from silanes of formula (1) and hydrolysis and condensation products thereof as described herein and further comprising a second silane or siloxane crosslinker selected from silanes of formula (II) and hydrolysis and condensation products thereof, wherein the silane of formula (II) is selected from the group consisting of methyltrimethoxysilane, chloromethyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, vinyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, silanetrimethoxysilane, methyltripropoxysilane, phenyltripropoxysilane, tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetra-n-butoxysilane, 2-aminoethyl-3-aminopropyltrimethoxysilane, 2-aminoethyl-3-aminopropyltriethoxysilane, N-phenylaminomethyltrimethoxysilane, 3-glyoxysilyloxypropyl bis-(N-methylacetamido)methylethoxysilane, tris- (methylethylketoximo)methylsilane, tris-(methylethylketoximo)vinylsilane, tris-(methylethylketoximo)phenylsilane, tris-(methylpropylketoximo)methylsilane, tris-(methylpropylketoximo)vinylsilane, tris-(methylpropylketoximo)phenylsilane, N,N-bis-(triethoxysilylpropyl )amine, N,N-bis-(trimethoxysilylpropyl)amine, 1,2-bis-(triethoxysilyl)ethane and combinations thereof, preferably selected from the group consisting of tris-(methylpropylketoximo)methylsilane, tris-(methylpropylketoximo) vinylsilane and tris-(methylpropylketoximo)phenylsilane, most preferably selected from the group consisting of tris-(methylpropylketoximo)methylsilane.

In particularly preferred embodiments of the invention there is provided the silicone formulation described herein comprising a first crosslinker selected from silanes of formula (I) as described herein and hydrolysis and condensation products thereof and a second

BE2021/5640 silane or siloxane cross-linker of formula (II) as described herein, wherein the weight ratio of the second cross-linker to the first cross-linker is in the range of 0.5 to 20, preferably in the range of 2 to 15 more preferably in the range of 6 to 12, most preferably in the range of 8 to 10.

In particularly preferred embodiments of the invention there is provided the silicone formulation described herein comprising a first crosslinker selected from silanes of formula (I) as described herein and hydrolysis and condensation products thereof and a second silane or siloxane crosslinker selected from silanes of formula (II) as described herein, wherein the weight ratio of the second crosslinker to the first crosslinker is in the range of 0.5 to 20, preferably in the range of 2 to 15, more preferably in the range of 6 to 12 , most preferably in the range of 8 to 10 and wherein the total amount of silane or siloxane crosslinkers is in the range of 2-8% by weight (based on total weight of the silicone formulation), preferably in the range of 4-6 wt%, most preferably in the range 4.5-5.5 wt%.

As will be appreciated by those skilled in the art from the present disclosure, in case the first crosslinker selected from silanes of formula (I) and hydrolysis and condensation products thereof is prepared in situ by reacting 5-methyl-3 heptanone as free oxime in combination with a silane or siloxane cross-linker, inevitably include a second silane or siloxane cross-linker (i.e., the unreacted portion of the silane or siloxane cross-linker used to form the silane according to formula (I)).

In particularly preferred embodiments of the invention there is provided the silicone formulation described herein comprising a first crosslinker selected from silanes of formula (I) as described herein and hydrolysis and condensation products thereof and a second silane or siloxane crosslinker selected from silanes of formula (II) as described herein and hydrolysis and condensation products thereof, wherein the hydroxy-terminal polydiorganosiloxane is at least partially end-capped with the first cross-linker and the second cross-linker. More preferably, substantially all of the terminal hydroxy groups of the polydiorganosiloxane are end-capped with the first cross-linker or the second cross-linker.

Silicone formulation obtainable by combining free oxime and silane cross-linker

As previously explained herein, the present inventors have found that the improved early cracking behavior and/or the improved sheeting time can also be obtained by using 5-methyl-3-heptanone as the free oxime in combination with a silane oxide. or siloxane crosslinker. Without wishing to be bound by theory, the present inventors believe that the combination of 5-methyl-3-heptanone oxime as free oxime with a silane or siloxane cross-linker leads to the in-situ formation of a 5-methyl-3 heptanone oxime-bearing silane.

40

Polydiorganosiloxane (base polymer)

According to the invention, the hydroxy-terminal polydiorganosiloxane included in the silicone formulations described herein may be a straight-chain or branched polydiorganosiloxane conventionally used in silicone formulations and is not particularly limited.

In embodiments of the invention, the hydroxy-terminal polydiorganosiloxane comprises diorganosiloxane repeating units of the structure [-SiR2RP-O-Jn, where n is such that the dynamic viscosity at 25°C of the resulting polymer is in the range of 100 to 500,000 mPa:s and wherein R 2 and RP are independently selected from the group consisting of methyl, ethyl, propyl, butyl, phenyl, methylphenyl, ethylphenyl, vinyl, allyl, cyclohexyl, tolyl, isopropyl, chloropropyl, 3,3,3-trifluoropropyl , chlorophenyl, beta-(perfluorobutylethyl and chlorocyclohexyl, preferably R 7 and RP are independently selected from the group consisting of methyl, ethyl, phenyl, vinyl or 3,3,3-trifluoropropyl, most preferably R 7 and RP are methyl .

In preferred embodiments of the invention, the hydroxy-terminal polydiorganosiloxane is a hydroxy-terminal polydialkylsiloxane, preferably hydroxy-terminal polydimethylsiloxane.

In preferred embodiments of the invention, the hydroxy-terminal polydiorganosiloxane has a dynamic viscosity at 25°C of at least 200 mPa:s, preferably at least 2000 mPa:s, more preferably at least 10,000 mPa:s.

In preferred embodiments of the invention, the hydroxy-terminal polydiorganosiloxane has a dynamic viscosity at 25°C of less than 350,000 mPa:s, preferably less than 200,000 mPa:s, more preferably less than 130,000 mPa:s.

Thus, the hydroxy-terminal polydiorganosiloxane in particularly preferred embodiments of the invention is a hydroxy-terminal polydialkylsiloxane, preferably a hydroxy-terminal polydimethylsiloxane having a dynamic viscosity at 25°C in the range of 200-350,000 mPa:s, with more preferably 2000-200,000 mPa:s, most preferably 10,000-130,000 mPa:s.

The determination of the dynamic viscosity of polysiloxanes is known to those skilled in the art. A preferred method to determine the dynamic viscosity of the hydroxy-terminal polydiorganosiloxane is in accordance with DIN53019-1 (2008).

In preferred embodiments of the invention, the hydroxy-terminal polydiorganosiloxane as described herein is present in an amount of greater than 10% by weight (based on total weight of the silicone formulation), preferably greater than 20% by weight, more preferably more than 30% by weight.

In preferred embodiments of the invention, the total amount of hydroxy-terminal polydiorganosiloxanes present in the formulation is in the range of 20-95% by weight (based on total weight of the silicone formulation), preferably 25-90% by weight. %, more preferably 30-80 % by weight.

40

Catalyst

In accordance with the invention, the silicone formulations described herein may further comprise a catalyst. In a particularly preferred embodiment, the catalyst is an organometallic catalyst present in an amount of 0.01-10% by weight (based on total weight of the silicone formulation). The catalyst may be any catalyst conventionally used in silicone formulations, such as organic bases, metal complexes, amines and/or carbenes, and is not particularly limited.

Examples of suitable organic bases are guanidine or amidines, such as C1-C4-alkylamidines.

Examples of suitable metal complexes, preferably organometallic complexes, are metal complexes wherein the metal is selected from the group consisting of Al, Bi, Co, Fe, Ga, La, Mn, Pb, Pd, Pt, Rh, Sc, Sn, Sr, Ti, TI, Y, Zn and Zr, more preferably wherein the metal is selected from the group consisting of Ti(IV), Sn(11), Sn(IV), Bi(IIT), Zn) and Zr( IV). Suitable complexing groups include, for example, alkyl groups, such as C1-C20 alkyl groups, and carboxylates, such as C2-C20 carboxylates.

Examples of suitable amines include secondary amines and tertiary amines, such as diazabicycloundecenes.

Suitable catalysts are e.g. those available under the trade name TIB KAT®, such as company types 216, 217, 218, 219, 221, 223, 226, 229, 232, 233, 248, 318 and 417 TIB Chemicals AG.

In preferred embodiments of the invention, the silicone formulations described herein are provided, further comprising a catalyst which is an organometallic catalyst, wherein the metal is selected from the group consisting of Al, Bi, Co, Fe, Ga, La, Mn, Pb, Pd, Pt, Rh, Sc, Sn, Sr, Ti, TI, Y, Zn and Zr, more preferably comprising a catalyst which is an organotin compound, more preferably an organotin compound selected from the group consisting of dimethyltin-di-2- ethyl hexanoate, dimethyltin dilaurate, di-n-butyltin diacetate, di-n-butyltin di-2-ethylhexanoate, di-n-butyltin dicaprylate, di-n-butyltin di-2,2-dimethyloctanoate, di-n- butyltin dilaurate, di-n-butyltin distearate, di-n-butyltin dimaleate, di-n-butyltin dioleate, di-n-octyltin di-2-ethylhexanoate, di-n-octytin di-2, 2-dimethyloctanoate, di-n-octyltin dimaleate, di-n-octyltin dilaurate, di-n-butyltin oxide and di-n-octyltin oxide, most preferably di-n-octyltin oxide.

In preferred embodiments of the invention, the silicone formulations described herein are provided, further comprising a catalyst as described herein, preferably an organometallic catalyst as described herein, wherein the catalyst is present in an amount greater than 0.01 wt% (on based on total weight of the silicone formulation), preferably greater than 0.05% by weight, more preferably greater than 0.1% by weight.

In preferred embodiments of the invention, the silicone formulations described herein are provided, further comprising a catalyst as described herein, wherein the catalyst is present in an amount of less than 10% by weight (based on total weight of the silicone formulation), preferably less than 5% by weight, more preferably less than 1% by weight.

In preferred embodiments of the invention, the silicone formulations described herein are provided, further comprising a catalyst as described herein, wherein the catalyst is present in an amount ranging from 0.01-10% by weight (based on total weight of the silicone formulation), preferably in the range of 0.05-5 wt%, more preferably in the range 0.1-1 wt%.

In accordance with the invention, the total combined amount of metal catalysts present is less than 10% by weight (based on total weight of the silicone formulation), preferably less than 5% by weight. filler

According to the invention, the silicone formulations described herein may further comprise a filler. The filler may be any filler conventionally used in silicone formulations and is not particularly limited. The term "filler" as used herein refers to reinforcing fillers (e.g., fumed silicic acid, precipitated calcium carbonate, or carbon black), as well as non-reinforcing fillers (e.g., ground calcium carbonate). Fillers can also act as rheology modifiers and vice versa (eg fumed silicic acid).

In accordance with preferred embodiments of the invention, the silicone formulations described herein are provided, further comprising a filler which is also a thickener. A preferred filler that is also a thickener is silica, also called silicic acid. Silicic acid is a weak acid derived from silicon dioxide, SiO2, with the general formula SiO2.nH20, where n can vary. Silica is preferred because it binds/interacts with the polymer backbone, bringing about a significant improvement in the physical and mechanical properties of the final product. The inventors have found that various forms of silica can be used as a thickener, but fumed silicic acid (also called "pyrogenic silica") is preferred because of its superior effect on mechanical properties of the final cured product (such as tear strength). Suitable fillers that act as thickeners are available e.g. as HDK® V15, V15A, N20, H13L, H15, H18 from the company Wacker, as Cabosil® L-90, LM-150, M-5, TS-610, TS- 622 from the Cabott company, as Aerosil® 130, 150, 200, R972, R974 from Evonik.

In preferred embodiments of the invention, the silicone formulations described herein are provided, further comprising a filler selected from the group consisting of mineral fillers, metal oxide fillers, fly ash, bottom ash, carbon black and combinations thereof, preferably selected from the group consisting of: chalk, calcium hydroxide; natural, ground or precipitated calcium carbonates; dolomites; fumed silicic acid; carbon black; calcined kaolins; boehmite; clay; talc; aluminum silicates; magnesium aluminum silicates; zirconium silicates; finely ground quartz; finely ground cristobalite; diatomaceous earth; mica; iron oxides; titanium oxides; zirconia and combinations thereof, more preferably selected from the group consisting of chalk, dolomite, fumed silicic acid and combinations thereof.

The filler may be surface modified. Surface modification of fillers is known to those skilled in the art. Preferred surface modifications include surface treatment with a fatty acid (e.g., stearic acid) or a silane (e.g., an alkoxysilane). The filler may be a reinforcing filler having a BET surface area of 90 to 300 m°/g, preferably 100 to 200 m°/g, more preferably 130 to 170 m°/g. The filler may be a non-reinforcing filler or a semi-reinforcing filler having a BET surface area of 2 to 90 m 2 /g, preferably 2 to 50 m 2 /g, more preferably 2 to 10 m 2 /g .

In preferred embodiments of the invention, the silicone formulations described herein are provided, further comprising a filler as described herein, wherein the filler is present in an amount greater than 1% by weight (based on total weight of the silicone formulation), preferably more than 3 wt%, more preferably more than 5 wt%.

In preferred embodiments of the invention, the silicone formulations described herein are provided, further comprising a filler as described herein, wherein the filler is present in an amount of less than 60% by weight (based on total weight of the silicone formulation), preferably less than 50% by weight, more preferably less than 30% by weight.

In preferred embodiments of the invention, the silicone formulations described herein are provided, further comprising a filler as described herein, wherein the filler is present in an amount in the range of 1-60% by weight (based on total weight of the silicone formulation) preferably in the range of 3-50% by weight, more preferably in the range of 5-30% by weight.

In preferred embodiments of the invention, the silicone formulations described herein further comprise 1-60% by weight (based on total weight of the silicone formulation), preferably in the range of 3-50% by weight, more preferably in the range of 5% -30 wt% of a filler selected from the group consisting of mineral fillers, metal oxide fillers, fly ash, bottom ash, carbon black and combinations thereof, preferably selected from the group consisting of: calcium hydroxide; natural, ground or precipitated calcium carbonates; dolomites; fumed silicic acid; carbon black; calcined kaolins; boehmite; clay; talc; aluminum silicates; magnesium aluminum silicates; zirconium silicates; finely ground quartz; finely ground cristobalite; diatomaceous earth; mica; iron oxides; titanium oxides; zirconia, more preferably selected from the group consisting of dolomite and fumed silicic acid.

In accordance with the invention, the total combined amount of fillers present is less than 60% by weight (based on total weight of the silicone formulation), preferably less than 50% by weight. Adhesion Promoter

According to the invention, the silicone formulations described herein may further comprise an adhesion promoter. The adhesion promoter may be any adhesion promoter conventionally used in silicone formulations and is not particularly limited.

In preferred embodiments of the invention, the silicone formulations described herein are provided, further comprising an organosilane adhesion promoter selected from the group consisting of aminosilanes, alkoxysilanes and epoxysilanes, preferably selected from the group consisting of aminoalkyltrialkoxysilanes, aminoalkylalkyldialkoxysilanes, bis(alkyltrialkoxysilyhamines (alkyltrialkoxysilyl)amines, tris(alkyltrialkoxysilyl)cyanuarates, tris(alkyltrialkoxysilyl)isocyanuarates, alkoxy-terminal polydimethylsiloxanes comprising aminoalkyl side groups (such as ethoxy-terminal (3-aminopropyl)(methyl)polysiloxane)), hydroxyoxane-terminal polydimethylsiloxane end-capped with N-(3-trimethoxysilyl)propylcyclohexanamine, condensation products of one of the mentioned silanes and combinations thereof. Preferably, the alkyl group is a C1-C4 alkyl and the alkoxy group is a C1-C4 alkoxy.

In particularly preferred embodiments of the invention, the silicone formulations described herein are provided, further comprising an adhesion promoter selected from the group consisting of 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3- aminopropyltrimethoxysilane, 3-(2-aminoethylamino)propyltriacetoxysilane, N-(3-trimethoxysilylpropyl)diethylenetriamine, bis-(3-methoxysilylpropyl)amine, aminoethylaminopropylmethyldimethoxysilane, N-(2-aminoethyl)- 3-aminopropyldimethoxymethylsilane, N-(n-butyl)-3-aminopropyltrimethoxysilane, N-(n-butyl)-3-aminopropyltrimethoxysilane, 3-aminopropylmethyldiethoxysilane, aminoethylaminotrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, gamma- ureidopropyltrimethoxysilane, 3-aminopropyl(methyl)silsesquioxanes and combinations thereof.

Suitable adhesion promoters can be found e.g. in the families of products offered as Geniosil® from the Wacker company, as Silquest® from Momentive Performance Materials and as Dynasylan® from Evonik.

In preferred embodiments of the invention, the silicone formulations described herein are provided, further comprising an adhesion promoter as described herein, wherein the adhesion promoter is present in an amount greater than 0.01 wt% (based on total weight of the silicone formulation), preferably more than 0.05 wt%, more preferably more than 0.1 wt%.

In preferred embodiments of the invention, the silicone formulations described herein are provided, further comprising an adhesion promoter as described herein, wherein the adhesion promoter is present in an amount of less than 10% by weight (based on total weight of the silicone formulation), preferably less than 5% by weight, more preferably less than 3% by weight.

In preferred embodiments of the invention, the silicone formulations described herein are provided, further comprising an adhesion promoter as described herein, wherein the adhesion promoter is present in an amount ranging from 0.01-10% by weight (based on total weight of the silicone formulation), preferably in the range of 0.05-5 wt%, more preferably in the range 0.1-2 wt%.

In accordance with the invention, the total combined amount of adhesion promoters present is less than 15% by weight (based on total weight of the silicone formulation), preferably less than 10% by weight. plasticizer

According to the invention, the silicone formulations described herein may further comprise a plasticizer. The plasticizer may be any plasticizer conventionally used in silicone formulations and is not particularly limited. Preferred plasticizers are silicone oils, which may be partially or completely replaced by C10-C20 hydrocarbons.

Thus, the silicone formulations described herein are provided in preferred embodiments of the invention, further comprising a plasticizer which is a straight or branched chain polydialkylsiloxane containing two or less hydrolyzable Si-O bonds, preferably a plasticizer which is a trialkylsilyl-terminal polydialkylsiloxane is preferably a trimethylsilyl-terminal polydialkylsiloxane. The linear or branched polydialkylsiloxane preferably has a dynamic viscosity at 25°C in the range of 1-10000 mPa:s, preferably a viscosity in the range of 10-12,500 mPa:s.

In preferred embodiments of the invention, the silicone formulations described herein are provided, further comprising a hydrocarbon plasticizer consisting of one or more C10 -C30 hydrocarbons, preferably consisting of one or more C10 -C20 hydrocarbons. Preferably, the hydrocarbon plasticizer comprises <10 wt% (based on total weight of hydrocarbon plasticizer) aromatics, preferably less than 3 wt% aromatics.

Such products are offered, for example, as Exxsol® D60, D80, D100, D120 or D140, or as Isopar® H, J, K, L, M, N or V from the company ExxonMobil Chemical, or Ketrul® D100, Hydroseal ® G232H, G240H, G3H, G250H, G270H, G400H, G310H, G315H, G340H from Total company, or Shellsol® D60, D80, D100 from Shell company, Pilot® 261, 291, 321, 400, 600, 900 from the company Petrochem Carless, or Nyflex® 8120, 8131, 800 of the company Nynas.

In embodiments of the invention, the silicone formulations described herein are provided, further comprising a plasticizer which is an alkyl end-capped poly(alkylene) glycol, preferably C1-C4 end-capped polyethylene or polypropylene glycol.

In preferred embodiments of the invention, the silicone formulations described herein are provided, further comprising a plasticizer as described herein, wherein the plasticizer is present in an amount greater than 1% by weight (based on total weight of the silicone formulation), preferably more than 3 wt%, more preferably more than 5 wt%.

In preferred embodiments of the invention, the silicone formulations described herein are provided, further comprising a plasticizer as described herein, wherein the plasticizer is present in an amount of less than 40% by weight (based on total weight of the silicone formulation), preferably less than 35 wt%, more preferably 40 less than 30 wt%.

In preferred embodiments of the invention, the silicone formulations described herein are provided, further comprising a plasticizer as described herein, wherein the plasticizer is present in an amount ranging from 1-60% by weight (based on total weight of the silicone formulation) preferably in the range of 10-50 wt%, more preferably in the range 20-35 wt% based on total weight of the silicone formulation.

In accordance with the invention, the total combined amount of plasticizers present is less than 50% by weight (based on total weight of the silicone formulation), preferably less than 35% by weight.

Miscellaneous

As will be appreciated by those skilled in the art, the silicone formulations described herein may contain additional ingredients (such as biocides, pigments, etc.) and the combined amount of all ingredients used in the silicone formulations is 100% by weight (based on total weight of the ingredients). silicone formulation).

In preferred embodiments of the invention, the silicone formulations described herein are provided wherein the total combined amount of a silane or siloxane cross-linker present is in the range of 0.1 to 15% by weight (based on total weight of the silicone formulation) is preferably in the range of 0.5 to 10% by weight, more preferably in the range of 1 to 6% by weight.

In particularly preferred embodiments of the invention, the formulations provided herein are vulcanizable at room temperature (e.g. 23°C), preferably moisture-curable and thus moisture-curable. In still more particularly preferred embodiments of the invention, the formulations provided herein are moisture curable, one component, room temperature vulcanizable (RTV1) silicone sealant formulations.

As will be appreciated by those skilled in the art, the silicone formulations described herein may be provided as one-component or multi-component systems (e.g., two-component systems). The silicone formulations described herein are preferably one-component systems.

In the event that the silicone formulations described herein are provided as a multi-component system, it should be understood that the relative amounts of the ingredients as defined herein are calculated on the basis of the total formulation as if the different ingredients were combined.

The present inventors have found that while silane or siloxane crosslinkers comprising at least one vinyl group (e.g., tris(alkoxy)vinylsilane or tris(alkoxime)vinylsilane) can be used to modify the early cracking behavior of known silane or siloxane To improve cross-linkers, the silicone formulation of the present invention requires less or even no silane or siloxane cross-linkers comprising at least one vinyl group to be free from early cracking. The compositions of the present invention, if not only extend sheeting time, improve early cracking behavior and improve one or more mechanical properties as explained elsewhere herein, they also utilize a lesser amount of silane or siloxane cross-linkers containing at least one vinyl group. potentially leading to additional benefits such as cost reduction and reduced or no gel formation during end capping (which is a typical issue with vinyl silanes). Thus, in preferred embodiments of the invention, there are provided the silicone formulations described herein comprising less than 4% by weight of silane or siloxane crosslinkers comprising at least one vinyl group (based on total weight of the silicone formulation), preferably less than 1% by weight. more preferably less than 01% by weight. In a particularly preferred embodiment, the silicone formulation is substantially free of a vinyl substituted silane or siloxane crosslinker. Likewise, the use of phenylsilanes can be avoided such that in preferred embodiments of the invention there are provided the silicone formulations described herein comprising less than 4% by weight of silane or siloxane crosslinkers comprising at least one phenyl group (based on total weight of the silicone formulation ), preferably less than 1% by weight, more preferably less than 0.1% by weight.

In a particularly preferred embodiment, the silicone formulation is substantially free of a phenyl-substituted silane or siloxane crosslinker. Preferably, the silicone formulations described herein are provided with lower vinyl substituted silane or siloxane crosslinker and lower phenyl substituted silane or siloxane crosslinker.

Further, in accordance with preferred embodiments of the invention, the silicone formulations described herein are provided having one or both of the following features: ° a skin forming time of greater than 10 minutes, preferably greater than 15 minutes; and ° an early cracking finish time of less than 30 minutes, preferably less than 20 minutes, more preferably less than 10 minutes, most preferably no early cracking.

In accordance with the invention, the skin formation time is determined according to the following method, carried out at room temperature (about 23°C) and about 50% relative humidity: a 2 mm thick film of silicone sealant is placed on a 400 µm PE film applied; ° at regular intervals, such as every minute, gently touch the top of the foil with a finger (or other utensil, such as a wooden chopstick), remove the finger or utensil and assess the skin formation; ° no skin formation is manifested by silicone material adhering to the finger (or other utensil) and a sharp spike of silicone material that protrudes from the surface after removal of the finger or utensil and ° skin formation is manifested by no silicone material sticking to the finger (or other utensil) clings and the absence of a sharp spike of silicone material protruding from the surface upon removal of the finger or utensil.

In accordance with the invention, the early cracking time is determined according to the following method, carried out at room temperature (about 23°C) and about 50% relative humidity: a 2 mm thick film of silicone sealant is placed on a 400 mm PE film um applied in a width of 5 cm and a length of 25 cm; ° every 5 minutes, the foil is bent 180° about the transverse axis (i.e. the curved path following the longitudinal axis) for 5 seconds with the silicone sealant on the outside, forming a bendline; ° the distance between the different bend lines is 2 cm, the first bend line being at least 2 cm from the top or bottom edge of the film; ° the time when cracks or cracks are first visible to the naked eye in the bendline is the 'early crack start time' and the time when no additional cracks or cracks appear is the 'early crack finish time' and ° the early crack start time is the difference between the 'early cracking end time' and the 'early cracking start time'.

If no cracks or cracks visible to the naked eye have formed in the bendline after 30 minutes of testing, the system is judged to show no early cracking.

Compounds of Formula (I)

As explained herein, the present inventors have found that the specific silanes comprising 5-methyl-3-heptanone oxime are useful as crosslinking agents in silicone formulations, especially silicone sealant formulations. Thus, in another aspect, the present invention provides an oxime silane or siloxane crosslinker selected from silanes of formula (I) and hydrolysis or condensation products thereof: iN sw) > {A Oje si-o RE / N= \ Ï ë \ PL) \ C7 \ RJ à AO (1) where: a is 0,1,2or3is bOor1; c is 1, 2, 3 or 4; a+b+c4is; each occurrence of R 1 and R 2 is individually selected from the group consisting of hydrogen and optionally substituted monovalent hydrocarbon radicals having 1 to 30 carbon atoms and

R3 and R* are such that each occurrence of R3 is methyl and R* is hydrogen.

In preferred embodiments of the invention, the oximesilane or siloxane crosslinker selected from silanes of formula (I) and hydrolysis or condensation products thereof is provided, wherein: each occurrence of R! individually selected from the group consisting of hydrogen, C1 -C8 alkyl, C1 -C8 haloalkyl, C1 -C8 aminoalkyl, C2 -C8 alkenyl, C3 -C8 cycloalkyl, C4 -C8 cycloalkenyl, C6 -C10 aryl, -C(O)R5 , -NECRER7 and -N=CRS:; RS, Rc and R' are selected from the group consisting of C1-C8-alkyl, C2-C8-alkenyl, C3-C8-cycloalkyl, C4-C8-cycloalkenyl and C3-C10-aryl; R 3 is a divalent C 2 -C 8 alkyl radical, so that -N=CR 3 is a cycloalkyl and R? is selected from the group consisting of hydrogen, C1 -C4 alkyl, C2 -C4 alkenyl and phenyl.

In preferred embodiments of the invention, the oximesilane or siloxane crosslinker selected from silanes of formula (I) and hydrolysis or condensation products thereof is provided, wherein: a is 0; b is O or 1, preferably 1; c is 3 or 4, preferably 3; a+b+c4is; R? is selected from the group consisting of hydrogen, C1 -C4 alkyl, C2 -C4 alkenyl and phenyl, preferably R1 . is selected from the group consisting of hydrogen, methyl, ethyl, vinyl and phenyl, more preferably R2 is methyl and R3 and R* are such that each occurrence of R* is methyl and R* is hydrogen.

In particularly preferred embodiments of the invention, the oximesilane or siloxane crosslinker selected from silanes of formula () and hydrolysis or condensation products thereof is provided, wherein: a is 0; b is 1; C3 is; a+b+c4is; R? is selected from the group consisting of hydrogen, C1 -C4 alkyl, C2 -C4 alkenyl and phenyl, preferably R1 . is selected from the group consisting of hydrogen, methyl, ethyl, vinyl and phenyl, more preferably R2 is methyl and R3 and R* are such that each occurrence of R* is methyl and R* is hydrogen.

Thus, in particularly preferred embodiments of the invention, the oximesilane or siloxane crosslinker selected from silanes of formula (I) and hydrolysis or condensation products thereof, preferably selected from silanes of formula (|), is provided. wherein the silane of formula (1) is a tris(5-methyl-3-heptanone oxime) silane, preferably methyl tris(5-methyl-3-heptanone oxime) silane, vinyl tris(5-methyl-3-heptanone oxime) silane or phenyl-tris(5-methyl-3-heptanone oxime) silane, most preferably methyl-tris(5-methyl-3-heptanone oxime) silane.

In preferred embodiments of the invention, the oximesilane or siloxane crosslinker selected from silanes of formula (I) and hydrolysis or condensation products thereof is provided, wherein: a is 2 or 3; boof1 is; c is 1 or 2; a+b+c4is; each occurrence of R' is individually selected from the group consisting of C1 -C4 alkyl, C2 -C4 alkenyl, phenyl, -C{O)R5, -N=CRSR7 and -N=CR8; R 8 , R 6 and R' are selected from the group consisting of C 1 -C 8 alkyl, C 3 -C 8 cycloalkyl and phenyl: R 3 is a divalent C 8 alkyl radical such that -N=CR 3 is cyclohexyl; R? is selected from the group consisting of hydrogen, C1 -C4 alkyl, C2 -C4 alkenyl and phenyl and R3 and R* are such that each occurrence of R3 is methyl and R* is hydrogen.

In more preferred embodiments of the invention, the oximesilane or siloxane crosslinker selected from silanes of formula () and hydrolysis or condensation products thereof is provided, wherein: a is 2 or 3; boof1 is; c is 1 or 2; a+b+c4is; R? is selected from the group consisting of hydrogen, C1 -C4 alkyl, C2 -C4 alkenyl and phenyl; R3 and R* are such that each occurrence of R3 is methyl and R* is hydrogen; R! -N=CRSR' is and R5 and R7 are selected from the group consisting of C1-C8-alkyl, preferably wherein Rc is methyl and —R' is propyl. Cured Silicone Formulation

In a further aspect of the invention there is provided a cured silicone formulation obtainable by curing a silicone formulation as described herein, preferably by moisture curing a silicone formulation as described herein. In a preferred embodiment of the invention there is provided a cured silicone formulation obtainable by curing a silicone formulation as described herein at a temperature in the range of 5-40 °C, preferably by moisture curing a silicone formulation such as described herein at a temperature in the range of 5-40 °C.

In preferred embodiments of the invention, a cured silicone formulation as described herein is provided which has one, two, three or four of the following characteristics: modulus of elasticity in the range of 0.15-0.5 MPa; 40° tensile strength of 0.8-2 MPa;

° elongation at break of 500-1500%; and ° shore A hardness of 8-20; where the modulus of elasticity, tensile strength and elongation at break are determined in accordance with DIN53504 (2017-03) using a film thickness of 2 mm, cured for 1 week at room temperature (23 °C) and the shore A hardness is determined in accordance with with 1SO868 (2003) using a film thickness of 6 mm. Use of the silicone formulation

In a further aspect of the invention, the use of the silicone formulation as described herein or the cured silicone formulation as described herein is provided as a sealant, joint compound or adhesive, preferably as a sealant. Use of the silanes according to formula (I)

In a further aspect of the invention, the use of a first crosslinker selected from silanes of formula ([) and hydrolysis or condensation products thereof as described herein is provided to improve early cracking behavior and/or extend sheeting time of a silicone formulation.

The invention also provides the use of a crosslinker selected from silanes of formula (|) and hydrolysis or condensation products thereof as described herein to reduce the amount of vinyl silane used in a silicone formulation.

The invention also provides the use of a crosslinker selected from silanes of formula (1) and hydrolysis or condensation products thereof as described herein, to reduce the carcinogenicity of a silicone formulation, preferably while reducing early cracking behavior and/or sheeting time. be maintained or improved.

The invention also provides the use of a crosslinker selected from silanes of formula (I) and hydrolysis or condensation products thereof as described herein to reduce the malodor caused by the curing of a silicone formulation, preferably while preserving the early cracking behavior. and/or the skin forming time is maintained or improved.

In accordance with preferred embodiments for the crosslinker described herein, the uses described herein preferably involve the use of a tris(5-methyl-3-heptanone oxime) silane, preferably a tris(5-methyl-3-heptanone oxime silane selected from the group consisting of methyl-tris(5-methyl-3-heptanone oxime) silane, vinyl-tris(5-methyl-3-heptanone oxime) silane and phenyl-tris(5-methyl-3-heptanone oxime) silane, most preferably methyl tris(5-methyl-3-heptanone oxime) silane.

Methods of Preparation of the Silicone Formulation

In another aspect of the invention there are provided methods for preparing the silicone formulations as described herein comprising the steps of:

(providing at least one hydroxy-terminal polydiorganosiloxane as described herein; (il) providing: (1.1) a crosslinker selected from silanes of formula (D and hydrolysis or condensation products thereof, as defined herein; (1.2) optionally a silane or siloxane crosslinker selected from silanes of formula (II) and hydrolysis or condensation products thereof, as described herein, (ill) optionally providing further components, and (iv) combining the in steps (i), ( ii) and optionally (iii) components provided.

Combining the ingredients provided in steps ( and (ii)) can be carried out in any conventional manner, such as by combining, mixing or stirring, preferably under a moisture-free atmosphere. not to be construed as being strictly limited to these components In the event that the silicone formulation comprises additional components (e.g., catalysts or fillers as described herein), step (iii) may comprise combining any optional additional components to form a silicone formulation as described herein. to obtain.

The order of combining is not particularly limited. In preferred embodiments, the compounds provided in step (ii.2) are first combined to form a crosslinker premix, which is then combined with the compounds provided in step ( and any optional further ingredients provided in step (iii).

As illustrated in the examples, it is preferred that the components provided in steps (1) and (ii) are combined before addition of optional further components such as catalysts, plasticizers, adhesion promoters, etc. This process leads to the so-called end capping the siloxane base polymer with the crosslinking agent and provides more efficient curing of the resulting silicone formulation.

In preferred embodiments, the method of preparing the silicone formulations as described herein further comprises a step of: (v) packaging the silicone formulation in an airtight container, such as an aluminum foil or plastic tube.

The invention further provides the following embodiments (A)-(P).

(A) A silicone formulation comprising a hydroxy-terminal polydiorganosiloxane, a catalyst and a first crosslinker selected from silanes of formula (I) and hydrolysis or condensation products thereof:

Ro} Si RN | a

AA | % | LC 7 X Hi ; \ ie) where: a0.1,20f3 is; boof1 is; c is 1, 2, 3 or 4; a+b+c4is; each occurrence of R 1 and R 2 is individually selected from the group consisting of hydrogen and optionally substituted monovalent hydrocarbon radicals having 1 to 30 carbon atoms; R* and R* are such that each occurrence of R* is methyl and R* is hydrogen, or each occurrence of R3 is hydrogen and R* is methyl and wherein the catalyst is an organometallic catalyst present in an amount of 0.01-10 wt% (based on total weight of the silicone formulation). (B) The silicone formulation according to embodiment (A), wherein each occurrence of R" is individually selected from the group consisting of hydrogen, C1-C8 alkyl, C1-C8 haloalkyl, C1-C8 aminoalkyl, C2-C8- alkenyl, C3 -C8 cycloalkyl, C4 -C8 cycloalkenyl, C5 -C10 aryl, -C(O)R5, -N=CRSR7 and -N=CR8, R5, R8 and R7 are selected from the group consisting of C1 -C8 alkyl, C2 -C8 alkenyl, C3 -C8 cycloalkyl, C4 -C8 cycloalkenyl and C5 -C10 aryl, R8 is a divalent C2 -C8 alkyl radical such that -N=CR3 ? is a cycloalkyl and R is selected from the group consisting of hydrogen, C1 -C4 alkyl, C2 -C4 alkenyl and phenyl (C) The silicone formulation of embodiment (B) wherein: a is 0, b is O or 1, preferably 1; c is 3 or 4, preferably 3, a+b+c4 is, R 7 is selected from the group consisting of hydrogen, C 1 -C 4 alkyl, C 2 -C 4 alkenyl and phenyl, preferably R 7 is selected from the group consisting of hydrogen, methyl, ethyl, vinyl and phenyl, more preferably R2 is methyl, and R* and R* are such that each occurs end case of R3 is methyl and R* is hydrogen, or any occurrence of R3 is hydrogen and R* is methyl. (D) The silicone formulation according to any one of embodiments (A)-(C), preferably according to embodiment (C), comprising a second silane or siloxane crosslinker selected from silanes of formula (II) and hydrolysis or condensation products thereof: {ro} SR (IN)

wherein: d is 3 or 4, preferably 3; e is 1 or O0, preferably 1; d+e4is; each occurrence of Rc is individually selected from the group consisting of hydrogen and optionally substituted monovalent hydrocarbon radicals having 1 to 30 carbon atoms, preferably each occurrence of Rc . individually selected from the group consisting of hydrogen, C1 -C8 alkyl, C1 -C8 haloalkyl, C1 -C8 aminoalkyl, C2 -C8 alkenyl, C2 -C8 cycloalkyl, C4 -C8 cycloalkenyl, C6 -C10 aryl, -C(O)R11, -N=CR12R13 and -N=CR1%, more preferably each occurrence of Rc is individually selected from the group consisting of C1 -C4 alkyl, C2 -C4 alkenyl, phenyl - C(O)R"*, -N=CR'2R13 and -N=CR"*, most preferably R° is N=CR"?R"3; R11 , R12 and R13 are selected from the group consisting of C1 -C8 alkyl, C2 -C8 alkenyl, C3 -C8 cycloalkyl, C4 -C8 cycloalkenyl and C5 -C10 aryl, preferably R11 , R12 and R13 are selected from the group consisting of C1-C4 alkyl, most preferably R!! and R°? are methyl and R ° C is propyl; R°* is a divalent C2-C8-alkyl radical such that -N=CR"* is a cycloalkyl and R'° is selected from the group consisting of hydrogen and optionally substituted monovalent hydrocarbon radicals having 1 to 30 carbon atoms, preferably R"° is selected from the group consisting of hydrogen, methyl, ethyl, vinyl and phenyl, more preferably R 10 is methyl.

(E) The silicone formulation according to embodiment (D), wherein the weight ratio of the second crosslinker to the first crosslinker is in the range of 0.5 to 20, preferably in the range of 2 to 15, more preferably in the range of 6 to 12, most preferably in the range of 8 to 10; and wherein the total amount of silane or siloxane crosslinkers is in the range of 2-8% by weight (based on total weight of the formulation), preferably in the range of 4-6% by weight, most preferably in the range of 4.5-5.5 wt%.

(F) The silicone formulation of any one of embodiments (A)-(E), wherein the hydroxy-terminal polydiorganosiloxane is at least partially end-capped with the first cross-linker.

(G) A silicone formulation obtainable by combining a hydroxy-terminal polydiorganosiloxane, a silane or siloxane crosslinker selected from silanes of formula (I) and hydrolysis or condensation products thereof, and a compound of formula (III); wherein the compound of formula (II) is: (IN) wherein d, e, R° and R° are as defined in embodiment (D); and the compound of formula (III) is:

RO Rt Nes

RE > R 11 wherein R 3 and R * are as defined in embodiment (A) and R 15 is selected from the group consisting of hydrogen and C 1 -C 4 alkyl, preferably R 15 is hydrogen. (H) The silicone formulation according to any one of embodiments (A)-(G), further comprising 1-60% by weight (based on total weight of the silicone formulation), preferably in the range of 3-50% by weight, with more preferably in the range of 5-30% by weight of a filler selected from the group consisting of mineral fillers, metal oxide fillers, fly ash, bottom ash, carbon black and combinations thereof, preferably selected from the group consisting of: calcium hydroxide; natural, ground or precipitated calcium carbonates; dolomites; fumed silicic acid; carbon black; calcined kaolins; boehmite; clay; talc; aluminum silicates; magnesium aluminum silicates; zirconium silicates; finely ground quartz; finely ground cristobalite; diatomaceous earth; mica; iron oxides; titanium oxides; zirconia, more preferably selected from the group consisting of dolomite and fumed silicic acid.

([) The silicone formulation according to any one of embodiments (A)-(H), having one or both of the following characteristics: ° a skin forming time of greater than 10 minutes, preferably greater than 15 minutes; and ° an early cracking finish time of less than 30 minutes, preferably less than minutes, more preferably less than 10 minutes, most preferably no early cracking.

(J) A cured silicone elastomer obtainable by curing the silicone formulation according to one of embodiments (A)-(1), preferably obtainable by moisture curing the silicone formulation according to one of embodiments (A) -([).

(A) Use of the silicone formulation according to any one of embodiments (A)-(1) as a sealant, joint compound or adhesive, preferably as a sealant.

(L) Use of a crosslinker selected from silanes of formula (I) and hydrolysis or condensation products thereof, as defined in any of the embodiments (A)-(C), preferably a crosslinker selected from silanes of formula (D) and hydrolysis or condensation products thereof as defined in embodiment (C), to improve the early cracking behavior of a silicone formulation; ° to extend the skinning time of a silicone formulation; ° reduce the amount of vinyl silane used in a silicone formulation; ° to reduce the carcinogenicity of a silicone formulation, preferably while maintaining or improving early cracking behavior and/or sheeting time;

° to reduce the malodor caused by the curing of a silicone formulation, preferably while maintaining or improving early cracking behavior and/or sheeting time.

(M) Use of a compound of formula (III) as defined in embodiment (G), to improve the early cracking behavior of a silicone formulation comprising a silane or siloxane crosslinker; ° to extend the skinning time of a silicone formulation comprising a silane or siloxane crosslinker; ° reduce the amount of vinyl silane used in a silicone formulation comprising a silane or siloxane crosslinker; ° to reduce the carcinogenicity of a silicone formulation comprising a silane or siloxane crosslinker, preferably while maintaining or improving early cracking behavior and/or sheeting time; ° to reduce the malodor caused by curing a silicone formulation comprising a silane or siloxane crosslinker, preferably while maintaining or improving early cracking behavior and/or sheeting time.

(N) A process for preparing a silicone formulation according to any one of embodiments (A)-(1) comprising the steps of: (providing at least one hydroxy-terminal polydiorganosiloxane; (il) providing at least one of the following: (1.1) a crosslinker selected from silanes of formula (D and hydrolysis or condensation products thereof, as defined in any of the embodiments (A)-(C), preferably a crosslinker selected from silanes of formula ([) and hydrolysis or condensation products thereof as defined in embodiment (C) and (1.2) a silane or siloxane crosslinker selected from silanes of formula (II) and hydrolysis or condensation products thereof, as described in embodiment (G), and a compound of formula (III) as described in embodiment (G) and (il) combining the components provided in steps (i) and (ii).

(0) An oxime silane or siloxane crosslinker selected from silanes of formula (D) and hydrolysis or condensation products thereof, as defined in embodiment (A), provided that the silane of formula (I) is not methyl-tris (2-heptanone oxime) silane, vinyl tris(2-heptanone oxime) silane or tetra(2-heptanone oxime) silane.

(P) The oximesilane or siloxane crosslinker of embodiment (O), wherein the silane of formula (I) is a tris(5-methyl-3-heptanone oxime) silane, preferably methyl-tris(5-methyl-3-heptanone oxime silane, vinyl tris(5-methyl-3-heptanone oxime) silane or phenyl tris(5-methyl-3-heptanone oxime) silane, most preferably methyl tris(5-methyl-3-heptanone oxime) silane.

For a proper understanding of this document and its claims, it is to be understood that the verb 'comprise' and its conjugations are used in its non-limiting sense to mean that points following the verb are included, but that points not specifically mentioned are not excluded. In addition, reference to an element with the indefinite article "a" does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements. The indefinite article 'a' usually means 'at least one'.

The terms first, second, third and the like in the specification and in the claims are used to distinguish between like elements and not necessarily to describe a sequential or chronological order. The terms are interchangeable under appropriate circumstances and the embodiments of the description may operate in orders other than those described or illustrated herein.

Furthermore, while the various embodiments are referred to as "preferred or "preferred embodiments", they are to be construed as exemplary of ways in which the invention may be applied, rather than as limiting the scope of the invention.

The invention will be further illustrated by the following examples, which are in no way intended to limit the scope of the invention.

Examples

A series of one-pack, RTV1, moisture-curable silicone sealant formulations comprising various oxime cross-linkers were prepared. The effect of the oxime crosslinker on the mechanical properties, sheeting time and early cracking behavior of the silicone formulation was evaluated.

The modulus of elasticity, tensile strength and elongation at break are determined in accordance with DIN53504 (2017-03) using a film thickness of 2 mm, cured for 1 week at room temperature (23°C) and the shore A hardness is determined in accordance with ISO868 (2003) using a film thickness of 6 mm. The early cracking time and the sheeting time were determined according to the methods previously described herein.

If no cracks or cracks visible to the naked eye have formed in the bendline after 30 minutes of testing, the system is judged to show no early cracking.

The sealant formulations comprise the following ingredients: hydroxyl terminal polydimethylsiloxane (PDMS) with a dynamic viscosity at 25°C of 80,000 mPa:s, PDMS silicone oil with a dynamic viscosity of 25°C at 1000 mPa:s, an oxime crosslinker as described in the following tables, hydrophilic fumed silica with a surface area of 150 m 2 /g (filler and thixotropic agent), aminopropyltrismethoxysilane (AMMO) (adhesion promoter) and dioctyltin oxide (DOTO) (catalyst).

The following oxime cross-linkers and oximes were used: 40° Me(MEKO) 3 Si: methyl-tris(methylethylketoximo)silane = methyl-tris(2-n-butanone oxime)silane e Me(ACO) 3 Si: methyl-tris (acetone oximo)silane = methyl-tris(2-propanone oxime) silane e Me(2PO)sSi: methyl-tris(2-pentanone oximo)silane e Vinyl(2PO)3Si: vinyl-tris(2-pentanone oximo)silane e Ph(2PO )3Si: phenyl-tris(2-pentanoneoximo)silane ° Me(MIBKO):3Si: methyl-tris(methylisobutylketoximo)silane = methyl-tris(4-methyl-2-pentanoneoxime)silane °Me(MAKO)sSi: methyl- tris(methylamylketoximo)silane = methyl-tris(2-heptanoneoxime)silane e Me(trem)3Si: methyl-tris(tremonoximo)silane = methyl-tris(5-methyl-3-heptanoneoxime)silane e Me(MiAKO):Si : methyl-tris(methylisoamylketoximo)silane = methyl-tris(5-methyl-2-hexanone oxime)silane e MAKO: methyl-amylketone oxime = 2-heptanone oxime (free oxime) e MEKO: methylethylketoxime = 2-butanone oxime (free oxime).

The silicone formulations were prepared on a high speed mixer using the following mixing steps: ° the hydroxy-terminal PDMS and the silicone oil were combined and the mixture was mixed at 3000 rpm for 30 seconds (mix 1); ° the crosslinker (crosslinker 1) was added to mixture 1 and the mixture was mixed for 30 seconds at 3000 rpm (mixture 2) and the resulting mixture 2 was kept at 25°C for 10 minutes; ° in case a second crosslinker was included, this second crosslinker (crosslinker 2) was added to mixture 2 and mixed at 3000 rpm (mixture 3) for 30 seconds and the resulting mixture 3 was kept at 25°C for 2 minutes; the hydrophilic fumed silicic acid was added to mixture 2 or mixture 3, respectively, and the mixture was mixed at 3000 rpm for 30 seconds (mixture 4); ° the adhesion promoter (AMMO) was added to mixture 4 and the mixture was mixed for 30 seconds at 3000 rpm (mixture 5); The catalyst (DOTO) was added to mixture 5 and the mixture was mixed at 3000 rpm for 30 seconds.

As shown in the tables below, the formulations comprising Me(MAKO) 3 Si or Me(trem) 3 Si have an extended sheeting time and show little or no cracking behaviour. Furthermore, this demonstrates that a combination of Me(MAKO) 3 Si and Me(2PO) 3 Si, either alone or added to the silicone formulation as a premixed mixture, also results in a silicone formulation having an extended skinning time and/or having little or no shows cracking behavior and also has increased shore A hardness compared to Me(MAKO)3Si alone. In addition, it was surprisingly found that even when used as free oxime, a mixture of Me(2PO):Si and MAKO results in a silicone formulation having an extended skin forming time and/or showing no cracking behaviour. The maximum stress, as mentioned in the following tables, is also referred to elsewhere herein as the tensile strength.

Example 1 Example 2 Example 3 Comparative UT | TE | PTE ms OH-functional PDMS |_Hydrophilic pyrogenic Mezelzuer() | 8 | 8 | 8 | B |

LL Modulus of elasticity Maximum stress Elongation at break

Comparative Comparative Comparative Comparative

OH-functional PDMS ee | 8 | #8 | ë |: LE qq

Modulus of elasticity

Maximum voltage

Elongation at fraction ee | mm | we | sm | me OO | Example® | Example 10 | Example 11 | Example12 |

OH-functional PDMS Pepe | | | † LL | † Formation time (min) | 8 | 9 TL 2 | 1 |

Modulus of elasticity

Maximum voltage

Elongation at break

LT VS T Veobeela 4] Voorbeela 15° | pre-order 16"

crosslinker 1 Me(MAKO)3Si/ Me(MAKO)3Si/

Me(2PO)sSi Me(2PO})sSi ee ae |

OH-functional PDMS renew | 5 | #8 |? † LL | † Formation time (min) | 20 | † 8 | †

Modulus of elasticity (MPa, DIN

Maximum stress (MPa, DIN 'The two cross-linkers are first mixed and added as a mixture to the silicone formulation (cross-linker 1). and a Vers [ Voobeald 19 |

Crosslinker 1 Me(MAKO)sSi/ Me(2PO})sSi/ Me(2PO})sSi/

Me(2PO)sSi MAKO MAKO [Ee me | peine | 8 | † † L 8 et | Formation time (min) oJ 8 TL BL | Maximum voltage (MPa DIN 53504) | 10 | MOT VO | aThe two compounds are first mixed and added as a mixture to the silicone formulation (crosslinker 1).

eeee eeee | crosslinker 1 Me(ACO)Si/ MAKO Me(2PO))sSi/ (Ratio MEKO Ta OH-functional PDMS Hydrophilic pyrogen Kieskuw@W | 8 | B | B |

OL arsenic) [9 [7 | 5 amo | | † “The two cross-linkers are first mixed and added to the silicone formulation as a mixture (cross-linker 1).

EE cross-linker 1 ee ee OH-functional PDMS Hydrophilic pyrogenic silica(@ |B | an [| a. The silicone formulation becomes tacky after curing.

Example 25 Comparative Example 27 Comparative Example 26 Example 28 OH-functional PDMS (80,000 mPa:s: g) 65 65 34 34 ren] B | B [| eos) [EE Early crack formation 10 (min.) 15 5 5 Early crack formation end 35 (min.) 30 45 0.24 0.40 0.30 (MPa, DIN 53504) 1.14 1.38 1.12 ( MPa, DIN 53504) 880 610 1000 (%; DIN 53504)

All compounds used except Me(trem) 3 Si are commercially available and obtained from various chemical suppliers.

Me(trem) 2 Si was synthesized as follows: To a two liter three-necked round bottom flask equipped with a thermometer, overhead stirrer and dropping funnel were added 436.8 (3.05 mol) of 5-methyl-3-heptanone oxime and 1000 ml hexane added. While stirring the contents of the flask, 74.5 g (0.5 mole) of methyltrichlorosilane was added dropwise from the dropping funnel over a period of 30 minutes. During the addition, the reaction temperature was maintained at 35-41°C. After the addition was complete, the reaction mixture was allowed to stand for 10 minutes. The upper phase containing hexane and the product was separated from the heavy lower phase of 5-methyl-3-heptanone oxime hydrochloride using a separatory funnel. The upper phase was neutralized with ammonia gas by bubbling the ammonia through the liquid for 10 minutes. Solid ammonium chloride was filtered off and hexane was removed from the filtrate by distillation under reduced pressure to obtain 214.9 g (91.5%) of a colorless liquid.

Claims (15)

Conclusions A silicone formulation comprising a hydroxy-terminal polydiorganosiloxane and a first crosslinker selected from silanes of formula (D1 and hydrolysis or condensation products thereof: | 8° > IR 0} Si — 9 RW j Nes \ p3/ \ IS \ ; † j X RJ N je (1) where a is 0,1,2or3is bOof1; c is 1, 2, 3 or 4; a+b+c4is; any occurrence of R* and R? individually selected from the group consisting of hydrogen and optionally substituted monovalent hydrocarbon radicals having 1 to 30 carbon atoms; and R3 and R* are such that each occurrence of R3 is methyl and R* is hydrogen. The silicone formulation of claim 1, further comprising a catalyst, preferably an organometallic catalyst present in an amount of 0.01-10% by weight (based on total weight of the silicone formulation). The silicone formulation of claim 1 or 2, wherein each occurrence of R! individually selected from the group consisting of hydrogen, C1 -C8 alkyl, C1 -C8 haloalkyl, C1 -C8 aminoalkyl, C2 -C8 alkenyl, C3 -C8 cycloalkyl, C4 -C8 cycloalkenyl, C6 -C10 aryl, -C(O)R*, -N=CR®R7 and -N=CRS; R5 , R8 , and R1 are selected from the group consisting of C1 -C2 alkyl, C2 -C8 alkenyl, C2 -C8 cycloalkyl, C4 -C8 cycloalkenyl and C6 -C10 aryl; R3 is a divalent C2 -C8 alkyl radical such that -N=CR3 is a cycloalkyl; and R? is selected from the group consisting of hydrogen, C1 -C4 alkyl, C2 -C4 alkenyl and phenyl. The silicone formulation of claim 3, wherein a is 0; b is O or 1, preferably 1; c is 3 or 4, preferably 3; a+b+c4is and R2 is selected from the group consisting of hydrogen, C1 -C4 alkyl, C2 -C4 alkenyl and phenyl, preferably R2 is selected from the group consisting of hydrogen, methyl, ethyl, vinyl and phenyl, with more preferably R 2 is methyl. A silicone formulation according to any one of claims 1 to 4, preferably according to claim 4, comprising a second silane or siloxane crosslinker selected from silanes of formula (II) and hydrolysis or condensation products thereof (01-81-0480) (IN) wherein: d is 3 or 4, preferably 3; e is 1 or 0, preferably 1; d+e4is; each occurrence of R° is individually selected from the group consisting of hydrogen and optionally substituted monovalent hydrocarbon radicals having 1 to 30 carbon atoms, preferably each occurrence of R° is individually selected from the group consisting of hydrogen, C1-C8 alkyl, C1 -C8 haloalkyl, C1 -C8 aminoalkyl, C2 -C8 alkenyl, C5 -C8 cycloalkyl, C4 -C8 cycloalkenyl, C5 -C10 aryl, -C(O)R1t, -N=CR"2R15 and -N =CR"*, more preferably each occurrence of Rc is individually selected from the group consisting of C1 -C4 alkyl, C2 -C4 alkenyl, phenyl, -C(O)R11 , -N=CR"2R13 and -N=CR"*, most preferably R° is N=CR12R13; R11 , R12 and R10 are selected from the group consisting of C1 -C8 alkyl, C2 -C8 alkenyl, C5 -C8 cycloalkyl, C4 -C8 cycloalkenyl and C6 -C10 aryl, preferably R1t , R12 and R1? are selected from the group consisting of C1 -C4 alkyl, most preferably R1 ! and R12 are methyl and R13 is propyl; R 1 * is a divalent C 2 -C 8 alkyl radical such that -N=CR" * is a cycloalkyl; and R 1 0 is selected from the group consisting of hydrogen and optionally substituted monovalent hydrocarbon radicals having 1 to 30 carbon atoms, preferably R 1 0 is selected from the group consisting of hydrogen, methyl, ethyl, vinyl and phenyl, more preferably R 10 is methyl and wherein the second silane or siloxane crosslinker selected from silanes of formula (II) and hydrolysis or condensation products thereof is different from the first crosslinker selected from silanes of formula (I) and hydrolysis or condensation products thereof. A silicone formulation according to claim 5, wherein the weight ratio of the second crosslinker to the first crosslinker is in the range of 0.5 to 20, preferably in the range of 2 to 15, more preferably in the range of 6 to 12, most preferably in the range of 8 to 10; and wherein the total amount of silane or siloxane crosslinkers is in the range of 2-8% by weight (based on total weight of the silicone formulation), preferably in the range of 4-6% by weight, most preferably in the range of 4.5-5.5 wt%. A silicone formulation according to any one of claims 1 to 6, wherein the hydroxy-terminal polydiorganosiloxane is at least partially end-capped with the first cross-linker. A silicone formulation according to any one of claims 1 to 7, further comprising 1-60% by weight (based on total weight of the silicone formulation), preferably in the range of 3-50% by weight, more preferably in the range range of 5-30% by weight of a filler selected from the group consisting of mineral fillers, metal oxide fillers, fly ash, bottom ash, carbon black and combinations thereof, preferably selected from the group consisting of: calcium hydroxide; natural, ground or precipitated calcium carbonates; dolomites; fumed silicic acid; carbon black; calcined kaolins; boehmite; clay; talc; aluminum silicates; magnesium aluminum silicates; zirconium silicates; finely ground quartz; finely ground cristobalite; diatomaceous earth; mica; iron oxides; titanium oxides; zirconia, more preferably selected from the group consisting of dolomite and fumed silicic acid. A silicone formulation according to any one of claims 1 to 8, having one or both of the following features: a skin forming time of greater than 10 minutes, preferably greater than 15 minutes, as determined using the method as defined in the detailed description ; and ° an early cracking finish time of less than 30 minutes, preferably less than 20 minutes, more preferably less than 10 minutes, most preferably no early cracking, as determined using the method as defined in the detailed description. A cured silicone elastomer obtainable by curing the silicone formulation according to any one of claims 1 to 9, preferably obtainable by moisture curing the silicone formulation according to any one of claims 1 to 9. Use of the silicone formulation according to any one of claims 1 to 9, or cured silicone elastomer according to claim 10, as a sealant, joint compound or adhesive, preferably as a sealant. Use of a first crosslinker selected from silanes of formula (I) and hydrolysis or condensation products thereof, as defined in any one of claims 1, 3 and 4, preferably a crosslinker selected from silanes of formula () and hydrolysis or condensation products thereof as defined in claim 4, to improve ° the early cracking behavior of a silicone formulation and/or ° prolong the skin formation time of a silicone formulation and/or ° reduce the amount of vinyl silane used in a silicone formulation and/or ° the carcinogenicity of a silicone formulation reduce the silicone formulation, preferably while maintaining or improving the early cracking behavior and/or the sheeting time and/or reducing the malodor caused by the curing of a silicone formulation, preferably while maintaining or improving the early cracking behavior and/or the sheeting time become. A process for the preparation of a silicone formulation according to any one of claims 1 to 9, comprising the steps of: (providing at least one hydroxy-terminal polydiorganosiloxane; (il) providing: (1.1) a first crosslinker selected from silanes of formula (I) and hydrolysis or condensation products thereof as defined in any one of claims 1, 3 and 4, preferably a crosslinker selected from silanes of formula (I) and hydrolysis or condensation products thereof as defined in claim 4 and (1.2) optionally a second silane or siloxane crosslinker selected from silanes of formula (II) and hydrolysis or condensation products thereof, as described in claim 5, (ill) optionally providing further components, and (iv) combining the ingredients provided in steps (i), (ij) and optionally (iii). An oxime silane or siloxane crosslinker selected from silanes of formula ([) and hydrolysis or condensation products thereof, as defined in claim 1. An oximesilane or siloxane crosslinker according to claim 14, wherein the silane of formula () is a tris(5-methyl-3-heptanone oxime) silane, preferably methyl-tris(5-methyl-3-heptanone oxime) silane, vinyl- tris(5-methyl-3-heptanone oxime) silane or phenyl-tris(5-methyl-3-heptanone oxime) silane, most preferably methyl-tris(5-methyl-3-heptanone oxime) silane.